Those errors are very common errors. I have this error one of our  EBS r12 instance

While I try to start my listener, I have errors, such as:

[oraprod@oracle]$ lsnrctl start LISTENER

TNS-12541: TNS:no listener
TNS-12560: TNS:protocol adapter error
TNS-00511: No listener
Linux Error: 111: Connection refused

I noticed that I have a missing entry on my /etc/hosts file as:

127.0.0.1       localhost.localdomain   localhost

After adding this line than I can start & stop listener without any problems.

Similar issue investigated in MOS [ID343295.1]